Abstract: A reflecting surface material for a vehicle interior, including multiple units of reflecting material each having a surface defined by a concave cross-sectional profile with at least one light reflecting face formed in one sector of the profile and at least one light absorbing face formed in another sector of the profile. A plurality of units of reflecting material are positioned such that the light reflecting faces are disposed in one direction toward the exterior of the vehicle and the light absorbing faces are disposed in another direction toward the driver of the vehicle.

Abstract: A method of making a micro corner cube array includes the steps of: preparing a substrate, at least a surface portion of which consists of cubic single crystals and which has a surface that is substantially parallel to {111} planes of the crystals; and etching the surface of the substrate anisotropically, thereby forming a plurality of unit elements for the micro corner cube array on the surface of the substrate. Each of these unit elements is made up of a number of crystal planes that have been formed at a lower etch rate than the {111} planes of the crystals.

Abstract: A method of making an array of corner cubes includes the steps of: preparing a substrate, at least a surface portion of which is made of a cubic crystalline material and which has a surface that is substantially parallel to {111} planes of the crystalline material; and patterning the surface of the substrate such that a plurality of solid shape elements defines a predetermined pattern on the surface of the substrate. Each of the solid shape elements is defined by a number of concave portions, a number of convex portions or a combination of concave and convex portions. The method further includes the step of supplying a first active species, including an element that is contained in the crystalline material, onto the substrate on which the solid shape elements have been formed.

Abstract: A cube corner array with minute modifications of the dihedral angles of some of the cube corners is produced by introducing a stress or change via the opposite side of the substrate. The array having aberrated elements can be replicated for use in the manufacture of a tool, and the tool can be used in the manufacture of retroreflective products of broader divergence.

Abstract: A ruling of cube corner elements comprising intersecting ruled vee-grooves is characterized in that at least one of the vee-grooves is made such the substrate being ruled and the cutting tool are oscillated with respect to one another during the ruling of the vee-groove. Rulings made in accordance with the instant invention can be designed to produce a cube corner element having broader divergence.

Abstract: The present invention provides a method of making a plurality of intrinsically retrochromic beads. The present invention further provides a kit comprising intrinsically retrochromic beads having different retroreflective colors.

Abstract: A layer composite of plastic material forms a retroreflector and includes at least one transparent structure layer, a protective layer and a reflection layer enclosed at the common interface between the structure layer and the protection layer. A relief structure formed by substantially identically shaped three-dimensional structure elements is formed in the reflection layer. At their base surfaces the structure elements are of lateral dimensions in the range of between 1 ?m and 100 ?m. The structure elements have side faces which are covered by the reflection layer and which include an angle of inclination of 45°, with a free surface of the layer composite. The relief structure is additively superimposed with a microstructure in at least one surface element. The microstructure has a preferred direction and influences the quality of the reflection action of the layer composite. The retroreflector is suitable for the production of machine-readable optical markings.

Abstract: Retroreflective sheeting and a method for making the same includes a plurality of open-faced cube-corner surfaces formed from a substantially rigid material to keep the cube-corner surfaces from flexing. An optical coating is formed on the surfaces, and a fill layer is attached to at least a portion of the optical coating. A plurality of voids form the open-faced cube-corner surfaces.

Abstract: The present invention provides a new sheeting article that may suitably include: a carrier having a first major surface and a second major surface; and a plurality of discrete segments of a sheeting (e.g., a retroreflective sheeting), wherein the sheeting has a first major viewing surface and a second major opposing surface, and the first major viewing surface of the sheeting is preferably removably attached to the second major surface of the carrier. Preferably, the first major surface of the carrier comprises a release surface, the second major opposing surface of the sheeting comprises an adhesive, the article is provided in the form of a roll, and the adhesive surface of the sheeting is adjacent the release surface of an adjacent layer of the roll. In a presently preferred embodiment the present invention provides novel easy-to-use truck conspicuity sheeting.

Abstract: A triangular-pyramidal cube-corner retroreflective sheeting wherein a pair of triangular-pyramidal cube-corner retroreflective elements partitioned by three lateral faces (face a1, b1, and c1; faces a2, b2, and c2; . . . ) intersect almost perpendicularly because intersecting V-shaped grooves having substantially-symmetric cross sections are arranged in a closest-packed state so as to protrude to one side on a common-bottom plane (S-S?). Opposite faces (faces c1 and c2) of this pair of triangular-pyramidal retroreflective elements share a base (x), the common bottom plane (S-S?) including bases (z and z) of one-side lateral faces (faces a1 and a2) and bases (y and y) of the other-side lateral faces (face b1 and b2), this pair of triangular-pyramidal retroreflective elements have faced lateral faces (face c1 and c2) with shapes, and heights from the bottom plane (S-S?) up to apexes of the elements, that differ from each other.

Abstract: The invention relates to articles comprising a sheeting having a microstructured surface that reflects light in a moiré-like pattern. The invention further relates to methods of making a master and replicas thereof including tooling that results in sheeting having such pattern. A preferred method comprises forming V-shaped grooves in a substrate (e.g. metal plate) wherein the intersections of three grooves form cube-corner elements. The cube-corner elements are formed in such a manner that adjacent parallel grooves have substantially the same groove spacing and groove depth throughout the array. The master as well as corresponding tooling and sheeting preferably have a groove spacing within the range of about 0.0005 inches (0.0127 mm) to about 0.007 inches (0.1778 mm) throughout the array and more preferably a groove spacing of less than about 0.004 inches (0.1016 mm).

Abstract: A rulable array of cube corners defined by three sets of parallel, equidistant, symmetrical vee-grooves is provided. The directions of the three vee-groove sets make three angles, no two of which are equal. When the array in viewed in plan, lines along the roots of the grooves determine a pattern of triangles in which the apices of the cube corners lie at distances from their respective triangle's centroid that are substantially less than the distance between the triangle's orthocenter and its centroid. In an unmetallized prismatic retroreflective sheeting, the array of quasi-triangular cube corners has the entrance angularity advantages of compound cant with nearly the efficiency of uncanted triangular cube corners at small entrance angles.

Abstract: A retroreflector assembly is assembled by adhering a retroreflector to a mounting member along a single flat back surface of the retroreflector and a flat surface of the mounting member. The retroreflector does not otherwise contact the mounting member. The retroreflector includes three plates having optically flat reflective front surfaces disposed at right angles to each other, wherein each of the plates further has a back surface disposed on an opposite side of the plate from the optically flat reflective front surface. The mounting member comprises a bonding portion and a base portion connected to the bonding portion, wherein the bonding portion is adhered to the back surface of one of the three plates, and wherein the bonding portion comprises a same material as the one of the three plates to which the bonding portion is adhered.

Abstract: The invention relates to a method of making retroreflective sheeting and other articles prepared from casting a moldable synthetic resin onto a tool having a microstructured surface.

Abstract: The first reflective lateral face of the first triangular-pyramidal retroreflective unit is on the same plane with the first lateral face of the tetrahedral retroreflective unit, the second reflective lateral face of the first triangular-pyramidal retroreflective unit is on the same plane with the second lateral face of the tetrahedral retroreflective unit, the third reflective lateral face of the first triangular-pyramidal retroreflective unit is parallel to one of the two lateral faces forming a V-shaped groove, the third reflective lateral face of the second triangular-pyramidal retroreflective unit is identical with, or parallel to, the other of the two faces forming said V-shaped groove, and the third reflective lateral face of said tetrahedral retroreflective unit is same as one of the two faces forming said V-shaped groove.

Abstract: A retroreflective structure is disclosed that has cube corner retroreflective elements. The structure includes a first array of retroreflective elements oriented in a first direction within a plane and a second array of retroreflective elements oriented in a second direction within the plane, wherein said second direction being about 90° to said first direction. The structure further includes a third array of retroreflective elements oriented in a third direction within the plane, wherein said third direction being about 180° to said first direction and a fourth array of retroreflective elements oriented in a fourth direction being about 270° to said first direction. In one embodiment, the retroreflective structure includes the retroreflective elements having cube corner elements having a pitch between elements in the range of between about 0.0035 and 0.0045 inches (0.088 and 0.114 millimeters).

Abstract: A cube corner array with minute modifications of the dihedral angles of some of the cube corners is produced by introducing a stress or change via the opposite side of the substrate. The array having aberrated elements can be replicated for use in the manufacture of a tool, and the tool can be used in the manufacture of retroreflective products of broader divergence.

Abstract: A retroreflective article comprises a) a microporous substrate (52) containing a plurality of pores (56) which are less than 0.5 ?m in diameter; and b) a layer of reflective material (54) located on the surface (58) of the substrate such that the reflective material layer at least partially obscures a plurality of the pores of the substrate. A method for the production of a reflective article comprises the steps of a) providing a substrate which contains pores which have a diameter of less than 0.5 ?m; and b) applying a layer of reflective material to the substrate in such a way that the reflective material layer at least partially obscures a plurality of the pores of the substrate.

Abstract: The invention relates to methods of making a master and replicas thereof including tooling and retroreflective sheeting. The invention further relates to the corresponding master, tooling and in particular retroreflective sheeting. The method comprises forming V-shaped grooves in a substrate (e.g. metal plate) wherein the intersections of three grooves form cube-corner elements. The cube-corner elements are substantially the same size throughout the array. The master as well as corresponding tooling and sheeting preferably have an average groove spacing within the range of about 0.0005 inches (0.0127 mm) to about 0.007 inches (0.1778 mm) throughout the array and more preferably an average groove spacing of less than about 0.004 inches (0.1016 mm).

Abstract: A fluorescent red-orange retroreflective article includes a polymeric matrix and at least one fluorescent dye added in an amount that provides the article with a red-orange color under daytime lighting conditions. The article also includes cube corner elements disposed at a back side of the polymeric matrix. The article can exhibit a retroreflectivity of at least 350 or 500 cd/(lux·m2), and a brightness Y of at least 20, 30, or 35. The article can exhibit a color within a preferred red-orange color space bounded by CIE chromaticity coordinates (0.560, 0.380), (0.580, 0.355), (0.633, 0.366) and (0.610, 0.390).

Abstract: To provide a triangular-pyramidal cube-corner retroreflective elements extremely superior in reflectivity at an entrance angle of 30° or more, preferably 40° or more. Triangular-pyramidal cube-corner retroreflective elements characterized in that when assuming the height from a bottom plane (Sx-Sx′) including base edges (x,x, . . . ) shared by two triangular-pyramidal reflective elements faced each other up to apexes (H1 and H2) of the triangular-pyramidal reflective elements as hx, the height from a bottom plane (Sy-Sy′) including other base edges (y,y, . . . ) of the triangular-pyramidal reflective elements as hy, and the height from a bottom plane (Sz—Sz) including still other base edges (z,z . . . ) of the triangular-pyramidal reflective elements as hz, any two of hx, hy, and hz are substantially different from each other and a mirror reflective layer is formed on surfaces of the triangular-pyramidal reflective elements.

Abstract: An integrated circuit enclosed retroreflective product which comprises an integrated circuit module having built-in integrated circuit(s), a retroreflective element, and their carrier layer(s).

Abstract: A method is disclosed for manufacturing a plurality of laminae for use in a mold suitable for use in forming retroreflective cube corner articles. Each lamina has opposing first and second major surfaces defining therebetween a first reference plane. Each lamina further includes a working surface connecting the first and second major surfaces. The working surface defines a second reference plane substantially parallel to the working surface and perpendicular to the first reference plane and a third reference plane perpendicular to the first reference plane and the second reference plane. The method includes orienting a plurality of laminae to have their respective first reference planes parallel to each other and disposed at a first angle relative to a fixed reference axis. At least two groove sets are formed in the working surface. Each groove set includes at least two parallel adjacent V-shaped grooves in the working surface of the laminae.

Abstract: To provide a retroreflective sheeting not only superior in high-brightness characteristic which is a basic optical characteristic generally requested for a triangular-pyramidal reflective element, that is, reflectivity represented by the reflectivity of the light incoming from the front of the triangular-pyramidal reflective element but also whose entrance angularity and rotation angularity are greatly improved. A pair of triangular-pyramidal cube-corner retroreflective elements characterized in that the optical axis of the triangular-pyramidal reflective element pair tilts so that the angle formed between the optical axis and a vertical line extended from apexes (H1 and H2) of the elements to a bottom plane (Sx-Sx′) ranges between 0.5 and 1.5° in the direction in which the difference (q−p) between the distance (q) from the intersection (Q) of the optical axis and the bottom plane (Sx-Sx′) up to base edges (x,x, . . .

Abstract: To provide a triangular-pyramidal cube-corner retroreflective sheeting having a new structure.

Abstract: A layer composite of plastic material forms a retroreflector and includes at least one transparent structure layer, a protective layer and a reflection layer enclosed at the common interface between the structure layer and the protection layer. A relief structure formed by substantially identically shaped three-dimensional structure elements is formed in the reflection layer. At their base surfaces the structure elements are of lateral dimensions in the range of between 1 &mgr;m and 100 &mgr;m. The structure elements have side faces which are covered by the reflection layer and which include an angle of inclination of 45°, with a free surface of the layer composite. The relief structure is additively superimposed with a microstructure in at least one surface element. The microstructure has a preferred direction and influences the quality of the reflection action of the layer composite. The retroreflector is suitable for the production of machine-readable optical markings.

Abstract: The invention relates to a method of making retroreflective sheeting and other articles prepared from casting a moldable synthetic resin onto a tool having a microstructured surface.

Abstract: The present invention is directed to lamina(e) comprising cube corner elements, a tool comprising an assembly of laminae and replicas thereof. The invention further relates to retroreflective sheeting.

Abstract: The present invention is directed to lamina(e) comprising cube corner elements, a tool comprising an assembly of laminae and replicas thereof. The invention further relates to retroreflective sheeting.

Abstract: A flexible mounting assembly is provided for a retroreflector assembly. The mounting assembly has a base member comprising three radial arms situated at substantially 120° from each other. In a preferred embodiment, a connector is mounted to the end of each arm, with the connector connecting the arm of the base to a resilient support member. Each support member has a pair of co-planar receiving surfaces, for receipt thereon of a mounting block, which mounting block is adhered to the underside of the retroreflector. The co-planar receiving surfaces of each of the support members are separated by a notch in the structure of the support member. In other embodiments, the radial arms of the mounting member and the connectors can be uniformly formed members. Another embodiment could have the mounting blocks an integrally formed part of the support members; i.e., integrally extending out from the co-planar surfaces.

Abstract: A display device includes a light modulating medium layer, a corner cube array and a reflective electrode layer. The corner cube array is provided on one side of the light modulating medium layer and includes multiple corner cubes as its unit elements. The reflective electrode layer is provided on the corner cube array and includes multiple reflective electrodes that are spaced apart from each other and that are used to apply a voltage to the light modulating medium layer. When the display device is viewed from over the corner cube array, an arrangement pattern of the corner cubes matches an arrangement pattern of the reflective electrodes in at least one direction.

Abstract: A method for tooling a pattern of retroreflective microcubes, which pattern can be subdivided into smaller increments within which there are straight line tooling paths, none of which pass through an otherwise solid part of the incremental pattern. The tooling paths within the various increments need not be parallel to a common plane. Various adaptions of the method enable the tooling of a number of specific microcube shapes and for modifying such optical properties of the microcubes as entrance angularity, incidence angularity, orientation angularity, observation angularity, percent active aperture and retroreflectance. Specific techniques govern the pre-selection of cube parameters such as cube axis cant, cube apex decentration, and cube boundary proportions, which parameters can be adjusted independently of each other. Designs tooled by the method can have 100% active aperture at near zero degrees entrance angle.

Abstract: An optical film is provided which comprises a disperse phase of polymeric particles disposed within a continuous birefringent matrix in combination with light directing materials to enable control of light emitted from a lighting fixture or display. The film is oriented, typically by stretching, in one or more directions. The size and shape of the disperse phase particles, the volume fraction of the disperse phase, the film thickness, and the amount of orientation are chosen to attain a desired degree of diffuse reflection and total transmission of electromagnetic radiation of a desired wavelength in the resulting film, and the light directing materials are chosen to control the direction of polarized light reflected from or transmitted by the optical film.

Abstract: A cube corner array with minute modifications of the dihedral angles of some of the cube corners is produced by introducing a stress or change via the opposite side of the substrate. The array having aberrated elements can be replicated for use in the manufacture of a tool, and the tool can be used in the manufacture of retroreflective products of broader divergence.

Abstract: A rulable array of cube corners defined by three sets of parallel, equidistant, symmetrical vee-grooves is provided. The directions of the three vee-groove sets make three angles, no two of which are equal. When the array in viewed in plan, lines along the roots of the grooves determine a pattern of triangles in which the apices of the cube corners lie at distances from their respective triangle's centroid that are substantially less than the distance between the triangle's orthocenter and its centroid. In an unmetallized prismatic retroreflective sheeting, the array of quasi-triangular cube corners has the entrance angularity advantages of compound cant with nearly the efficiency of uncanted triangular cube corners at small entrance angles.

Abstract: A see-through retroreflective structure includes a transparent polymeric film, an array of retroreflective elements attached to the polymeric film, and an array of apertures through the retroreflective structure within the array of retroreflective elements. In one embodiment, the retroreflective structure includes a metalized reflective layer formed on the transparent prism elements and a support layer, such as a fabric, is attached to the metalized reflective layer. The method includes providing a transparent polymeric film. An array of retroreflective elements is attached to the polymeric film. The array of retroreflective elements and the transparent polymeric film are perforated through the retroreflective structure to form an array of apertures, thereby forming a retroreflective structure. The apertures are of sufficient size and spacing to provide a see-through capability.

Abstract: A stain resistant film construction that includes a polyvinyl film laminated to a polyolefin film by an adhesive. The stain resistant film construction can be formed into a retroreflective product that includes a polyolefin layer, an adhesive layer and a polyvinyl layer attached to the polyolefin layer by the adhesive on the first side of polyvinyl layer. Retroreflective prisms can be attached to the second side of polyvinyl layer, and a backing layer can be attached to the second side of polyvinyl film through the prism layer.

Abstract: To provide a triangular-pyramidal cube-corner retroreflective sheeting having a novel structure characterized in that a lateral face (face c) using a base edge (x) of triangular-pyramidal reflective elements faced each other and arranged in the closest-packed state by sharing the base edge (x) on a first bottom plane (virtual plane X-X′) forms a triangle, two other faces (faces a and b) sharing one ridge line started from an apex (H) of the triangular-pyramidal reflective elements form a quadrangle, and the height (h′) from the apex (H) up to the first bottom plane (virtual plane X-X′) is substantially smaller than the height (h) from the apex (H) up to the substantially horizontal second bottom plane (Z-Z′) including base edges (z and w) of the other lateral faces (faces a and b).

Abstract: Retroreflective articles having multilayer films are useful for commercial graphics and retroreflective products, such as roll-up signs for highway transportation safety. The articles comprise multilayer films having at least one layer of polyurethane and at least one layer of a copolymer of alkylene and at least one non-acidic, polar co-monomer. Articles having the new multilayer films provide the same or improved performance, are less expensive, and offer improved methods for manufacturing, when compared to prior articles.

Abstract: A retroreflective structure and method for forming the same are provided which includes a polyurethane sheet having a first side and a second side, a coating on the first side, and an array of retroreflective prism elements formed on the coating. The coating is used to promote adhesion between the prism elements and the first side of the polyurethane sheet. A second coating can be formed on the second side of the polyurethane sheet for purposes such as forming a protective layer over the polyurethane sheet and can include ultraviolet blocking material.

Abstract: An article comprising (a) a curved substrate having a surface energy below about 38 dynes/cm2; (b) flexible retroreflective sheeting; and (c) a crosslinked pressure-sensitive adhesive adhering the sheeting to the curved substrate. The adhesive contains sufficient polar monomer and tackifier, and is sufficiently crosslinked, to (i) have a glass transition temperature less than −15° C., (ii) permit the sheeting to remain firmly bonded to a low density polyethylene barrel without buckling when cooled from 49° C. to −1° C., and (iii) provide an adhesive bond to the barrel that exhibits increased energy absorption when tested for impact resistance at 0° C. according to ASTM D4272. The adhesive can be manufactured by partially polymerizing some of the ingredients in a pouch using UV radiation, dispersing the pouch and its contents in the other ingredients using an extruder, extrusion coating the adhesive and then UV crosslinking the coating.

Abstract: A method of making an array of corner cubes includes the steps of: preparing a substrate, at least a surface portion of which is made of a cubic crystalline material and which has a surface that is substantially parallel to {111} planes of the crystalline material; and patterning the surface of the substrate such that a plurality of solid shape elements defines a predetermined pattern on the surface of the substrate. Each of the solid shape elements is defined by a number of concave portions, a number of convex portions or a combination of concave and convex portions. The method further includes the step of supplying a first active species, including an element that is contained in the crystalline material, onto the substrate on which the solid shape elements have been formed.

Abstract: A process for making a retroreflective article that includes the steps of providing a device (tool or a mold) having a first structured surface; applying a reflective layer on the first structured surface resulting in a first adhesion value between the reflective layer and the first structured surface, the reflective layer having an exposed surface; applying a molding polymer to the exposed surface of the reflective layer resulting in a second adhesion value between the reflective layer and the molding polymer. The second adhesion value is higher than the first adhesion value. The device is separated from the molding polymer to yield a retroreflective article that has a second structured surface that is the reverse image of the first structured surface. The separation causes a transfer of the reflective layer from the first structured surface to the retroreflective article.

Abstract: The invention relates to articles comprising a sheeting having a microstructured surface that reflects light in a moiré-like pattern. The invention further relates to methods of making a master and replicas thereof including tooling that results in sheeting having such pattern. A preferred method comprises forming V-shaped grooves in a substrate (e.g. metal plate) wherein the intersections of three grooves form cube-corner elements. The cube-corner elements are formed in such a manner that adjacent parallel grooves have substantially the same groove spacing and groove depth throughout the array. The master as well as corresponding tooling and sheeting preferably have a groove spacing within the range of about 0.0005 inches (0.0127 mm) to about 0.007 inches (0.1778 mm) throughout the array and more preferably a groove spacing of less than about 0.004 inches (0.1016 mm).

Abstract: The invention relates to methods of making a master and replicas thereof including tooling and retroreflective sheeting. The invention further relates to the corresponding master, tooling and in particular retroreflective sheeting. The method comprises forming V-shaped grooves in a substrate (e.g. metal plate) wherein the intersections of three grooves form cube-corner elements. The cube-comer elements are substantially the same size throughout the array. The master as well as corresponding tooling and sheeting preferably have an average groove spacing within the range of about 0.0005 inches (0.0127 mm) to about 0.007 inches (0.1778 mm) throughout the array and more preferably an average groove spacing of less than about 0.004 inches (0.1016 mm).

Abstract: Retroreflective sheeting includes a body layer having a structured surface with recessed faces and top surfaces, the recessed faces forming cube corner cavities. The recessed faces have a high specular reflectivity, while the top surfaces have a low specular reflectivity. In some embodiments a substantially continuous film of reflective material covers the structured surface, and a masking substance is provided over the reflective material at the top surfaces. Alternatively, the top surfaces are given a non-smooth surface finish so that the film of reflective material on those portions has a diffuse reflectivity. In other embodiments the film of reflective material is discontinuous, disposed selectively on the recessed faces and not on the top surfaces. A cover layer is also provided, and can bond at least to the top surfaces. Keeping the top surfaces substantially free of reflective material inhibits corrosion and can enhance the bond integrity.

Abstract: Sheeting material is disclosed that contains a retroreflective layer and a layer of luminescent material on the bottom or lower surface of the retroreflective layer. The sheeting material can be formed into signage or decorative articles that are highly visible under a variety of lighting conditions. A portion of the retroreflective layer is visible through the luminescent layer or through one or more openings in the luminescent layer which are in the form of slits, perforations, alphanumeric or other patterns. The luminescent layer can be imaged using analog or digital printing processes. The sheeting material can be made from materials that are suitable for back-lit illumination. Adhesives or other conventional attachment means can be employed to anchor the signs in interior or exterior environments.

Abstract: A method and apparatus for making retro-reflective articles are described which can be made without visually disturbing seam lines, In one embodiment molds having retro-reflective elements have serrated edges along boundary lines of retro-reflective elements are used. In another embodiment the molds are provided with mold lines aligned with edges of the molds and so spaced from the edges that molds can be placed adjacent to one another as part of a grid pattern wherein seam lines are a part of the grid pattern and thus visually hidden. In another embodiment, rather than grid lines being introduced into the molds used to form retro-reflective sheets, the grid lines are formed directly on or in the retro-reflective material itself during or after creation. Articles made with molds having mold lines exhibit a regular grid pattern, but without an asymmetric seam line appearing on the article.

Abstract: A retroreflective structure includes a retroreflective sheeting having an array of transparent prisms formed into pairs of prisms. Each prism includes a base aperture and three intersecting lateral faces meeting at an apex. Each of the lateral faces includes a base edge which forms a portion of the perimeter of the base aperture. The base edge of each lateral face intersects the base edge of a contiguous lateral face to form a base point, the first face of at least one prism in the array including a first face first planar surface and a first face second planar surface. The first face first planar surface and the first face second planar surface are contiguous along an edge having a first and second end points, wherein the apex, the first end point, and a first base point are coplanar and form a continuous edge from the first base point to the apex.

Abstract: An external resonator type wavelength variable light source comprises a semiconductor laser 5 formed on one end face with a antireflection coating 5a, a lens 6 for converting emitted light from the end face of the semiconductor laser 5 formed with the antireflection coating 5a into collimated light, a diffraction grating 7 for selecting a wavelength of the collimated light provided through the lens 6 and diffracting the light, and a mirror for reflecting the light diffracted through the diffraction grating 7 and feeding back the light again diffracted through the diffraction grating 7 into the semiconductor laser 5 through the lens 6. A V-groove grating mirror 8 having reflecting faces with an arrangement like a grating, of a plurality of V grooves 2 each shaped like V at right angles in cross section in a base material 1 with a reflection coating 3 formed on the surface of each V groove is used as the mirror.